Engines, for example vehicle engines, have included aspirators and/or check valves for a long time. Typically, the aspirators are used to generate a vacuum that is lower than engine manifold vacuum by inducing some of the engine air to travel through a venturi. The aspirators may include check valves therein or the system may include separate check valves. When the check valves are separate they are typically included downstream between the source of vacuum and the device using the vacuum.
In engines that include a brake boost system, conditions exist that may make it difficult for a check valve to seal effectively. In particular the sealing in a check valve may be less than desired at low temperatures and/or low sealing pressure differentials. Moreover, the engine system may require, or the manufacturer may specify, a weight limit for a check valve. One way to address the weight is to reduce the weight of the movable sealing member within the check valve. Reducing the weight however can exacerbate the problem of sealing in particular its ability to withstand large sealing pressure differentials.
Currently available check valves have a check valve assembly with a check valve disk made from a compliant material in order for the disk to conform to the manufacturing variations of a sealing surface. Good sealing is required even at low pressure difference across the disk. When the pressure difference becomes large sealing is assured, so long as the disk does not deform sufficiently so as to lift off the sealing surface. In addition, large stresses can be induced inside a compliant disk due to the resulting forces in a high pressure difference.
A rigid disk material will not effectively seal when lightly loaded; however, it will withstand the high load better than a non-rigid disk. This is a need to provide more efficient sealing under each condition at some time during operation of the system.